The convex
shape of ECT reflects these features. The molecular weights
of phenyl sulfide and benzyl sulfide are approximately 200
g/mol. The side chain of these compounds is aromatic group.
The remarkable increases of the ECT were not detected in
insulating oil containing these two compounds. The estimated
reason is that the aromatic group on the side chains is large,
works as a steric hindrance and disturbs the transformation of
sulfide compounds. It is concluded from these test results that
the influence of ECT varies depending on the molecular
weight and side chain type.